3,823 research outputs found
Correlations in local measurements on a quantum state, and complementarity as an explanation of nonclassicality
We consider the classical correlations that two observers can extract by
measurements on a bipartite quantum state, and we discuss how they are related
to the quantum mutual information of the state. We show with several examples
how complementarity gives rise to a gap between the quantum and the classical
correlations, and we relate our quantitative finding to the so-called classical
correlation locked in a quantum state. We derive upper bounds for the sum of
classical correlation obtained by measurements in different mutually unbiased
bases and we show that the complementarity gap is also present in the
deterministic quantum computation with one quantum bit.Comment: 15 pages, 4 figures, references adde
Atomic quantum superposition state generation via optical probing
We analyze the performance of a protocol to prepare an atomic ensemble in a
superposition of two macroscopically distinguishable states. The protocol
relies on conditional measurements performed on a light field, which interacts
with the atoms inside an optical cavity prior to detection, and we investigate
cavity enhanced probing with continuous beams of both coherent and squeezed
light. The stochastic master equations used in the analysis are expressed in
terms of the Hamiltonian of the probed system and the interaction between the
probed system and the probe field and are thus quite generally applicable.Comment: 10 pages, 9 figure
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